1. An electron entering Thomson's e/m apparatus (Figure 3.2 and 3.3) has an initial velocity (in horizontal direction only) of 0.7 107 m/s. Lying around the lab is a permanent horseshoe magnet of strength 1.3 10-2 T, which you would like to use.

Figure 3.2

Figure 3.3

(b) When the magnetic field is turned off, but the same electric field remains, how large a deflection will occur if the region of nonzero E and B fields is 2 cm long?

2. Light from a slit passes through a transmission diffraction grating of 330 lines/mm, which is located 2.2 m from a screen. What are the distances on the screen (from the unscattered slit image) of the three brightest visible (first-order) hydrogen lines?

3. (a) Estimate the power radiated by a 25 cm diameter basketball at 18°C.

(b) Estimate the power radiated by a human body (assume a tempertare of 37°C). (Approximate this as a rectangular solid of dimensions 1.9 m by 0.3 m by 0.2 m.)

4. A photon having 27 keV scatters from a free electron at rest. What is the maximum energy that the electron can obtain?